A mystical word which the Masons claim can give telepathic powers, if you know what it is. Unfortunately, it's been lost for centuries, so they have a substitute word they use to test people who claim to be Masons. The modern, substitute Mason Word is:
Mah-hah-bone.
Use it wisely, grasshopper.
Source: "Everything is Under Control: Conspiracies, Cults, and Cover-Ups" by Robert Anton Wilson, p. 294.